Avalanche Forecast

Issued: Feb 23rd, 2013 8:45AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Cornices.

Peter, Avalanche Canada

Northwest Coastal.

The heaviest snowfall will likely be confined to the coast with the approaching system. The avalanche danger could be slightly lower in areas that receive less than 20 cm of new snow through Sunday.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Tuesday

Weather Forecast

Synopsis: The active weather pattern continues into next week with a series of frontal systems affecting the region with short breaks in between each pulse.Overnight and Sunday: The first system arrives late Saturday bringing 10-15 cm overnight, and an additional 10-15 cm on Monday morning. The freezing level is around 600 m and winds are strong from the southwest. Monday: Cloudy with sunny breaks. The freezing level is near valley bottom and winds ease to light from the northwest. Tuesday: The next system arrives bringing 5-10 cm of snow and increasing winds.

Avalanche Summary

Several natural slab and loose wet avalanches up to size 2 were reported on Friday. There was also a report of a couple intentionally triggered slab avalanches up to size 2 that were 80 cm deep. Observations are generally limited to below treeline due to poor weather.

Snowpack Summary

Up to 100 cm of storm snow has fallen over the past few days. The new snow was reported to be dry and low density with no notable weaknesses. Deep and dense wind slabs have likely formed in exposed lee terrain and cross-loaded gullies. This new snow fell on a crust, old wind slab, and/or surface hoar depending on aspect and elevation. Most areas are reporting that the snow has bonded well to the underlying melt-freeze crust. Cornices that now loom over many features may become weak with continued growth and/or daytime warming. The mid and lower snowpack layers are generally well settled and strong.

Problems

Storm Slabs

It may be possible to trigger deep storm slabs in any terrain over 35 degrees, and particularly exposed lee terrain and cross-loaded gully features where wind slabs have formed.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Stick to non-avalanche terrain or small features with limited consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Cornices

Cornices have grown large and weak and may pop off with continued growth or during periods of mild sunny weather.

Give cornices a wide berth when travelling on or below ridges.>Avoid steep slopes below cornices.>

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Feb 24th, 2013 2:00PM